Loss of heterozygosity and overexpression of the p53 gene in ovarian carcinoma

Eight anticonvulsant drugs-including clonazepam, diazepam and phenobarbital-were tested for their effects on GABA-stimulated chloride uptake in rat cerebral cortical microsacs (unfiltered synaptoneurosomes). "Mid" and "high" therapeutic concentrations were screened, and, if significant enhancement was found, full concentration-response tests were done. In the initial screens, enhancement of GABA-stimulated uptake was found only with phenobarbital, clonazepam and diazepam. In subsequent concentration-response tests, the effects of phenobarbital were found to occur throughout the range of normal, anticonvulsant concentrations, whereas the effects of clonazepam and diazepam were observed only above the concentrations normally used for the chronic control of seizures or anxiety. These data suggest that phenobarbital's anticonvulsant effects are mediated via the GABAA receptor complex, but that the low-dose effects of the benzodiazepines may be mediated via some other mechanism.     

Gene transfer of calbindin D28k cDNA via herpes simplex virus amplicon vector decreases cytoplasmic calcium ion response and enhances neuronal survival following glutamatergic challenge but not following cyanide

Excitatory amino acid overstimulation of neurons can lead to a marked rise in cytoplasmic Ca2+ concentration ([Ca2+])i) and be followed by neuron death from hours to days later. If the rise in [Ca2+]i is prevented, either by removing Ca2+ from the extracellular environment or by placing Ca2+ chelators in the cytosol of the stimulated cells, the neurotoxicity associated with excitotoxins can be ameliorated. We have recently shown that neurons infected with a herpes simplex virus amplicon vector expressing cDNA for calbindin D28k responded to hypoglycemia with decreased [Ca2+]i and increased survival relative to controls. We now report that vector-infected neurons respond to glutamatergic insults with lower [Ca2+]i than controls and with increased survival. Infected neurons exposed to sodium cyanide did not respond with lower [Ca2+]i than controls, nor did they demonstrate increased survival postinsult. We examine these results in light of our earlier report and in the context of the potential of vectors like this for neuronal gene therapy.     

Subcritical interlaminar crack growth in fibre composites exhibiting a risingR-curve

Subcritical crack growth behaviour has been evaluated in composite laminates based on uniaxial carbon fibres in poly(ether-ether ketone) matrices. Double cantilever beam (DCB) specimens have been employed to give mode I loading and it is first shown that the materials exhibit a risingR-curve, i.e. the value of the interlaminar fracture energy,G _IC, increases as the crack propagates through the specimens. Secondly, when a DCB specimen is held at a constant displacement, subcritical crack growth is found to occur. The velocity of the subcritical crack growth,v, has been measured using a load-relaxation technique. Hence, values of the crack velocity,v, have been obtained as a function of the strain-energy release rate,G _I applied during subcritical crack growth. Owing to the presence of theR-curve, these data have been measured at various stages during the development of theR-curve. The relationships betweenv andG _I are modelled using power-law expressions. Finally, it is considered that theR-curve behaviour is most likely caused by the fibre bridging which develops behind the crack tip as the delamination propagates through the specimen. Fibre bridging allows stress to be transferred across the crack faces, behind the advancing crack tip, and so results in a shielding of the stress field at the crack tip from the applied stress. Therefore, the expression ascertained for the relationship between the velocity,v, of subcritical crack growth and the corresponding value ofG _I has been further refined and modelled to account for the presence of fibre bridging.     

Fabrication and measurement of low-stress membrane mirrors for adaptive optics

We have fabricated low-stress membranes from single-crystal silicon for use as deformable mirrors in adaptive optics. These membranes have lower stress than membranes made from silicon nitride or other materials and therefore are capable of greater deformation than previously used membrane mirrors. Membranes were assembled into devices by flip chip bonding to electrode chips with either 256 or 1024 electrodes. We have characterized devices with static and dynamic tests and compared their performance with an analytical model. We tracked the evolution of strain in the membrane during the device's fabrication and assembly and identified sources of stress and strain in this process. We identified boron dopant concentration as a critical determinant of intrinsic stress in the membrane.     

Electrospray mass spectrometric characterization of bimetallic group 8 — Gold clusters

Bimetallic clusters containing gold in conjunction with Group 8 metals have been intensively studied as it is proposed that these compounds may find uses as catalysts or materials (or as precursors to catalysts/materials). These types of compounds are very difficult to characterize by the mass spectrometric techniques traditionally used to analyse transition metal clusters. In this paper we report a derivatization method employing electrospray ionization mass spectrometry that is reliable and informative for these types of compounds.     

Long-wavelength stability of an unsupported multilayer liquid film falling under gravity

The long-wavelength stability of an unsupported multilayer liquid film falling under the effects of gravity and surface tension is investigated. By considering the Navier–Stokes equations for two fluid layers in the high-Reynolds-number and small-aspect-ratio limits the steady-state solutions are obtained. The stability criterion found by Lin (J Fluid Mech 104:111–118, 1981) for a one-layer fluid curtain is generalised to the two-layer case and the criterion for an n-layer curtain is established.     

Fathers and mothers of school-age children with developmental disabilities: parental stress, family functioning, and social support

Thirty pairs of fathers and mothers who had school-age children with mental retardation and other disabilities were compared with each other and with 32 father and mother pairs of parents of children without disabilities. Responses to family scales indicated that fathers and mothers of children with developmental disabilities did not differ from each other nor from fathers and mothers of children without disabilities in parental stress, family social support, or family functioning. However, parents of children with disabilities experienced a disproportionately greater level of stress relating to their children than did those of children without disabilities. Fathers' and mothers' stress was associated with aspects of family functioning as perceived by themselves and their spouses.